Pipe connections mentioned at the beginning are known very well from the prior art. For example, DE 1 960 933 U discloses a connection piece as part of such a pipe connection, said connection piece being able to be welded to a pipe end. The known connection piece is in this case plugged into an at least partially complementary connection piece, wherein the two connection pieces are screwed together by way of a union nut. In this case, the conical sealing surfaces are pressed against one another, with the result that a leaktight pipe connection is produced. The pipe connection is used at least for conducting hydraulic oil. However, it has been shown that such connections can become untight when fluids having a varying or different temperature are conducted, for example when converting from a gaseous or liquid fuel to a line flushing medium.